(1) Field of the Invention
This invention relates to a structure and process for controlling and removing particulate in product handling.
(2) Description of the Related Art
As used herein, the term "product" or "granule" refers to grain, coal, rocks, lie soap, fertilizer, or any product that has particulates. Although the product will normally be an agricultural product and a grain such as wheat, sorghum, corn, oats, rye, barley, and the like, it will be understood that it could also be other agricultural products such as peas, beans, vegetable seed, and the like. "Product" or "granule" is also meant to include extremely small product size such as what might be considered to be powder including gravel, sand, soil or powdered lime, or other industrial material. "Particulate" is meant to include all very fine material, and particularly that material that is held in suspension by air moving at a velocity of 2,000 feet per minute and is picked up and re-entrained in the air moving at a velocity of 3,500 feet per minute.
In this regard, when the term "conveyed" or "conveyor" is used, it is intended that it be used in its broadest sense of moving product from one location to another location. Typical of conveyors of product would be bucket lifts, belt conveyors, and also inclined chutes or pipes and discharge transition.
Particulate, in a smooth pipe, will have an angle of repose of about 55.degree.. In commercial practice, before my invention, particulate was moved in horizontal pipes with the air velocity of 3,500 feet per minute to keep the particulate suspended and to re-entrain the particulate. See ALLINGTON, U.S. Pat. No. 1,048,477; ALLINGTON, U.S. Pat. No. 840,894, and BUDD ET AL., U.S. Pat. No. 1,629,991. Thus, when a process was being interrupted and the fans cut off, the particulate in the pipe would fall to the bottom of the pipe. Particulate remains in suspension at 2,000 feet per minute, but experience indicates a velocity of 3,500 feet per minute is needed to pick up and re-entrain particulate when it is on the bottom of a pipe. See Industrial Ventilation, 18th edition, 1984 American Conference of Government Industrial Hygienist, Cincinnati, Ohio, pages 4-7. Thus, fans having sufficient power to move the air at 3,500 feet per minute were used.
In the harvesting of agricultural product, the product will often have particulate matter associated with it. E.g., insects, bees wing, red dog chaff, plant particles such as bits of stems, leaves, parts of the grain heads, and the like. Furthermore, in handling and conveying the product, the friction of the product against itself will abrade some of the product; and therefore, each time the product is handled, additional particulate is produced. It is well known that when agricultural particulate is mixed in the air and enclosed, it forms an explosive mixture.
It has long been a desire to control the particulate in bucket elevators and to remove as much particulate as possible and particularly to keep as much particulate from being within the air as possible. Likewise, it has been recognized that it is desirable to clean the product to remove everything from the product except the product itself. This includes all particulates discussed above. According to the prior art before my invention, normally the removal of foreign matter was carried on in different processes than the removal of the dust itself. See HEDLEY, U.S. Pat. No. 3,400,816.
Before this invention, the removal of dust was characterized by removing the dust from a portion of any conveyor closure which was remote from the stream of the conveyed product. E.g., see DELIVUK, U.S. Pat. No. 2,482,159; DOWDALL, U.S. Pat. No. 1,508,682; DOWDALL, U.S. Pat. No. 1,562,946; PALMER, U.S. Pat. No. 2,617,531; LORENZEN, U.S. Pat. No. 2,415,503; PATTERSON, U.S. Pat. No. 2,513,963; and Industrial Ventilation, pages 5-36, 5-37, and 5-38.
Axial flow fans within an air conduit are known. ZACK, U.S. Pat. No. 4,515,071; Industrial Ventilation, pages 10-2 and 10-3.
Industrial Ventilation, pages 11-27 and 11-28 shows typical equipment for separating dust from air.
Also, the practice before this invention was to place the fan at a distance remote from where the air was removed from the conveyor. It was not unlikely that the fan would be at or beyond the point where the dust was separated from the air. It was characteristic to use on collecting fan for several intakes of particulate. See Industrial Ventilation, 4-7. Therefore, it was necessary to increase the diameter of pipe, but yet it was necessary that the pipe not be increased to such a point till the velocity was less than 3,500 feet per minute. Industrial Ventilation pages 6-36 shows a typical increase in diameter.
Before this application was filed, the applicant caused a search to be made in the U.S. Patent and Trademark Office. In addition to the patents discussed above, the following patents were found on that search:
SCHNEIBLE ET AL: 2,579,401 PA1 FRASIER ET AL: 3,016,813 PA1 ARALT: 3,870,168 PA1 CARPENTAR: 4,241,517 PA1 (1) to move the air in the particulate tube and spout in a cycloning path. PA1 (2) to connect the particulate tube into the discharge transition on the product conveyor. PA1 (3) to place the aluminum fan at about eight diameters from the particulate port. PA1 (4) to move the particulate at low velocity (2,000 fpm) to conserve energy and help separation of particulate from product. PA1 (5) to remove the air and particulate from the product conveyor at the particulate port in as close proximity as possible to the stream of the product. PA1 (6) that the particulate tubes carrying the air from the product conveyor be angled downward at an angle of 60.degree. or greater as soon as possible. PA1 (7) to increase the discharge particulate spout in diameter to maintain low velocities, and PA1 (8) to store the particulate in the same bin wherein it is separated from air.
Applicant does not consider these patents as pertinent as those specifically discussed above, but believes the Examiner would consider anything revealed by an experienced patent searcher to be relevant and pertinent to the examination of this application.